Linear drive system for use in a plasma processing system

ABSTRACT

A plasma processing system for processing a substrate is disclosed. The system includes a process component capable of effecting a plasma inside a process chamber. The system also includes a gear drive assembly for moving the process component in a linear direction during processing of the substrate.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/012,265 filed Nov. 5, 2001, now U.S. Pat. No. 6,669,811 issued Dec.30, 2003, which is a continuation of U.S. patent application Ser. No.09/474,843 filed Dec. 30, 1999, now U.S. Pat. No. 6,350,317 issued Feb.26, 2002 and which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to apparatuses and methods for processingsubstrates such as semiconductor substrates for use in IC fabrication orpanels (e.g., glass, plastic, or the like) for use in flat panel displayapplications. More particularly, the present invention relates toimproved methods and apparatuses for moving components associated withprocessing a substrate.

Plasma processing systems have been around for some time. Over theyears, plasma processing systems utilizing inductively coupled plasmasources, electron cyclotron resonance (ECR) sources, capacitive sources,and the like, have been introduced and employed to various degrees toprocess semiconductor substrates and display panels. In a typical plasmaprocessing application, the processing source gases (such as the etchantgases or the deposition source gases) are introduced into a processchamber. Energy is then provided to ignite a plasma in the processingsource gases. After the plasma is ignited, it is sustained withadditional energy, which may be coupled to the plasma in variouswell-known ways, e.g., capacitively, inductively, through microwave, andthe like. The plasma is then employed in a processing task, e.g., toselectively etch or deposit a film on the substrate.

During deposition, materials are deposited onto a substrate surface(such as the surface of a glass panel or a wafer). For example,deposited layers such as various forms of silicon, silicon dioxide,silicon nitride, metals and the like may be formed on the surface of thesubstrate. Conversely, etching may be employed to selectively removematerials from predefined areas on the substrate surface. For example,etched features such as vias, contacts, or trenches may be formed in thelayers of the substrate.

In processing the substrates, one of the most important parameters thatengineers strive to improve is process uniformity. As the term isemployed herein, process uniformity refers to the uniformity across thesurface of a substrate, the uniformity between different substratesprocessed in the same process chamber, and the uniformity betweendifferent substrates processed in different process chambers. If theprocess is highly uniform, for example, it is expected that the processrates at different points on the substrate, as well as process ratesbetween different substrates in a production run, tend to besubstantially equal. In either case, it is less likely that one area ofthe substrate will be unduly over-processed while other areas remaininadequately processed or that one substrate will be processeddifferently than another substrate. As can be appreciated, processuniformity is an important determinant of yield and therefore a highlevel of process uniformity tends to translate into lower costs for themanufacturer.

In many applications, process uniformity is difficult to maintainbecause of variations found in various parameters associated withprocessing a substrate. By way of example, the wafer area pressure(WAP), i.e., pressures surrounding the surface of the substrate, mayfluctuate during a run of substrates because of temperature changesproximate the substrate. As is well known to those skilled in the art,if the WAP is higher for one substrate and lower for another substratethe desired processing performance between the substrates tends to benon-uniform. Additionally, if the WAP is higher across one area of thesubstrate and lower across another area of the substrate the desiredprocessing performance across the surface of the substrate tends to benon-uniform.

One technique for controlling the WAP has been to provide a confinementring inside the process chamber. The confinement ring is generallyconfigured to surround the substrate in the active region, which istypically above the substrate to be processed. In this manner, theprocessing performed is more confined and therefore the WAP is moreuniform. Although this technique works well for a number ofapplications, in many applications it would be desirable to provide amore controlled processing environment that can adaptively change toaccommodate variations in the WAP during processing of a singlesubstrate, during processing of a plurality of substrates in aproduction run or during processing in different chambers.

Recently, there have been some efforts to provide a moving confinementring that can adjust the exhaust conductance and therefore the WAP. Inthis manner, the WAP can be controlled to reduce variations that mightoccur during processing. One particular approach uses a cam system tomove the confinement ring up and down between upper and lowerelectrodes. In this approach, a circular cam with varying levels on itssurface is perpendicularly engaged with a plunger/spring mechanism thatis connected to the confinement ring. As the cam turns, the plunger ismoved up or down according to the different levels on surface of thecam, and as a result the confinement ring correspondingly moves up ordown. Accordingly, the cam mechanism can be configured to control thegap between the confinement ring and lower electrodes so as to adjustthe exhaust conductance and therefore the WAP in the active region abovethe substrate.

Although this technique generally works well, one problem is that theconventional cam approach provides only a limited range of pressurecontrol, low sensitivity and low resolution (i.e., low precision). Byway of example, the slope or level of the surface of the cam is limitedby the plunger/cam interface because the plunger may get stuck if theslope is too large. As a result, the overall distance the plunger movesis restricted, which leads to the limited range of pressure control.Further, precise changes in the pressure during processing cannot beperformed with the conventional cam approach. Further still, theplunger/cam interface may wear and the spring may loose springiness,both of which tend to reduce the reliability of the system.

Among the important issues to manufacturers is the cost of ownership ofthe processing tool, which includes, for example, the cost of acquiringand maintaining the system, the frequency of chamber cleaning requiredto maintain an acceptable level of processing performance, the longevityof the system components, and the like. Thus a desirable process isoften one that strikes the right balance between the differentcost-of-ownership and process parameters in such a way that results in ahigher quality process at a lower cost. Further, as the features on thesubstrate become smaller and the process becomes more demanding (e.g.,smaller critical dimensions, higher aspect ratios, faster throughput,and the like), engineers are constantly searching for new methods andapparatuses to achieve higher quality processing results at lower costs.

In view of the foregoing, there is a need for improved methods andapparatuses for moving components (i.e., a confinement ring) associatedwith processing a substrate.

SUMMARY OF THE INVENTION

The invention relates, in one embodiment, to a plasma processing systemfor processing a substrate. The system includes a process componentcapable of effecting the plasma within the process chamber. The systemfurther includes a gear drive assembly for moving the process componentin a linear direction during processing of the substrate.

The invention relates, in another embodiment, to a plasma processingsystem for processing a substrate. The system includes a confinementring for confining a plasma inside a process chamber. The system alsoincludes a gear drive assembly for moving the confinement ring in alinear direction during the processing of the substrate.

The invention relates, in another embodiment, to a plasma processingsystem for processing a substrate. The system includes an electrode forgenerating an electric field inside a process chamber. The system alsoincludes a gear drive assembly for moving the electrode in a lineardirection during the processing of the substrate.

The invention relates, in another embodiment, to a plasma processingsystem for processing a substrate. The system includes an electrode forgenerating an electric field inside a process chamber. The system alsoincludes a confinement ring for confining a plasma inside the processchamber. The system further includes a gear drive assembly for movingthe confinement ring or the electrode.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIG. 1 is a broken away, perspective view of a plasma reactor, inaccordance with one embodiment of the present invention.

FIG. 2 is a side elevation view, in cross section, of the plasma reactorof FIG. 1.

FIG. 3 is a top elevation view, in cross section, of the plasma reactorof FIG. 1.

FIG. 4 is a flow diagram depicting the relevant steps involved inprocessing a substrate in the plasma reactor of FIGS. 1-3, in accordancewith one embodiment of the present invention.

FIG. 5 is a broken away, perspective view of a plasma reactor, inaccordance with one embodiment of the present invention.

FIG. 6 is a broken away, perspective view of a plasma reactor, inaccordance with one embodiment of the present invention.

FIG. 7 is a top elevation view, in cross section, of the plasma reactorof FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in detail with reference toa few preferred embodiments thereof as illustrated in the accompanyingdrawings. In the following description, numerous specific details areset forth in order to provide a thorough understanding of the presentinvention. It will be apparent, however, to one skilled in the art, thatthe present invention may be practiced without some or all of thesespecific details. In other instances, well known process steps have notbeen described in detail in order not to unnecessarily obscure thepresent invention.

The present invention provides a linear drive assembly that is capableof moving a body associated with processing a substrate with a highdegree of movement control. The linear drive assembly includes aplurality of gears that are operatively engaged with one another. Thelinear drive assembly also includes a plurality of positioning membersthat are movably coupled to a predetermined set of the gears andstructurally coupled to a movable body. The positioning members areconfigured to move the body in a linear direction when the predeterminedset of gears are rotated. In one specific application, the positioningmembers are shafts having external threads that are configured to matewith internal threads of the predetermined set of gears.Correspondingly, when the predetermined set of gears are rotated, therotation of the gears rotate the internal thread, which in turn causesthe shaft to move in the linear direction. Accordingly, the use of gearsand threads provide a high degree of control of linear movements of thebody. For example, the gear/thread arrangement allows for more precisemovements with increased resolution, sensitivity and reliability.

The invention relates, in one embodiment, to a plasma processing systemthat is capable of a high degree of processing uniformity control. Theplasma processing system is configured for processing a substrate andincludes a process chamber, a lower electrode, an upper electrode and aconfinement ring that are employed to both generate the plasma and tocontain the plasma for the processing task

In accordance with one aspect of the present invention, the linearmotion of the linear drive assembly is configured to control the gapbetween the confinement ring and the lower electrode during processing.In particular, the linear drive assembly is arranged to move theconfinement ring up and down, between the upper electrode and the lowerelectrode, to adjust the exhaust conductance. By adjusting the exhaustconductance, the pressure (i.e., WAP) inside the active region above thesubstrate may be maintained at a desired level for processing.Accordingly, the pressure can be controlled with little variation duringprocessing to provide increased process uniformity, which increasessubstrate throughput, reduces device failure, and increases the overallproductivity of the substrates being processed.

In accordance with another aspect of the present invention, the linearmotion of the linear drive assembly is configured to control the gapbetween the upper electrode and the substrate during processing. Inparticular, the linear drive assembly is arranged to move the upperelectrode up and down to adjust the volume of the active region abovethe substrate. By adjusting the volume, various parameters associatedwith plasma processing, such as the plasma density and pressure, may bemaintained at desired levels for processing. Similarly, the plasmadensity and pressure can be controlled with little variation duringprocessing to provide increased process uniformity, which increasessubstrate throughput, reduces device failure, and increases the overallproductivity of the substrates being processed.

In accordance with another aspect of the present invention, the linearmotion of the linear drive assembly is configured to independentlycontrol the gap between the confinement ring and the lower electrode andthe gap between the upper electrode and the substrate during processing.In this particular embodiment, the linear drive assembly is reconfiguredto include additional gears. For example, the linear drive assembly alsoincludes a second set of predetermined gears and positioning members. Inthis manner, the first set of predetermined gears and positioningmembers are configured to move the confinement ring and the second setof predetermined gears and positioning members are configured to movethe upper electrode. A transfer gear is also included to operativelyengage or disengage the predetermined gears from the first gear.Accordingly, because both gaps are controlled, the process engineer hasincreased control over the processing conditions surrounding thesubstrate to be processed.

In a preferred embodiment, the present invention is practiced in aplasma reactor, such as the capacitively coupled plasma reactor, whichis available from Lam Research Corporation of Fremont, Calif. Although acapacitively coupled plasma reactor will be shown and described, itshould be noted that the present invention may be practiced in anyplasma reactor that is suitable for forming a plasma, such as aninductively coupled or an ECR reactor.

FIGS. 1 and 2 illustrate a simplified schematic of plasma reactor 100,according to one embodiment of the invention. The plasma reactor 100generally includes a plasma processing chamber 102. Inside chamber 102,there is disposed an upper electrode 104 and a lower electrode 106.Upper electrode 104 is disposed above lower electrode 106 and is coupledto a first RF power supply 108 via a matching network (not shown tosimplify the illustration). First RF power supply 108 is configured tosupply upper electrode 104 with RF energy. Additionally, lower electrode106 is coupled to a second RF power supply 110, which is configured tosupply lower electrode 106 with RF energy.

Furthermore, the gap 111 between the upper and lower electrode 104, 106generally determines the volume of an active region during processing.Therefore, the size of gap 111 can be configured to control variousparameters such as the pressure and/or plasma density. While not wishingto be bound by theory, it is believed that a smaller volume may increaseplasma density and a larger volume may decrease plasma density. As iswell known to those skilled in the art, the plasma density tends toeffect the rate of processing, for example, the etch rate.Correspondingly, the gap may be configured to balance the desired volumeand thus the desired etch rate for processing

Further still, it is generally believed that the gap 111 plays animportant role in controlling the pressure inside the active regionabove the substrate. As a general rule, the pressure is inverselyproportional to the volume, where a decrease in the volume correspondsto an increase in pressure, and an increase in the volume corresponds toa decrease in pressure. Accordingly, the size of the gap 111 ispreferably configured to balance the desired volume with the desiredpressures for processing.

Plasma reactor 100 also includes a chuck 112, which is disposed on thetop surface of the lower electrode 106. The chuck 112 is configured tohold a substrate 114 during processing. Chuck 112 may represent, forexample, an ESC (electrostatic) chuck, which secures substrate 114 tothe chuck's surface by electrostatic force. Additionally, substrate 114represents the work-piece to be processed, which may represent, forexample, a semiconductor substrate to be etched, deposited, or otherwiseprocessed or a glass panel to be processed into a flat panel display.

Further, a gas port 116 for releasing gaseous source materials, e.g.,the etchant source gases, into the active area between the upperelectrode and the substrate is typically provided within process chamber102. As illustrated in FIG. 2, gas port 116 is disposed inside the upperelectrode 104. Additionally, an exhaust port 118 for exhaustingby-product gases formed during processing is generally disposed betweenthe chamber walls of the process chamber and the lower electrode 106. InFIG. 2, exhaust port 118 is coupled to a pump 120 located at the bottomof chamber 102. The pump 120 is generally arranged to maintain theappropriate pressure inside chamber 102. In one implementation, aturbomolecular pump is used.

By way of example, in order to create a plasma, a process gas is inputinto chamber through the gas port 116. Power is then supplied to theelectrodes 104 and 106 and a large electric field is produced betweenthe upper and lower electrodes 104 and 106. As is well known in the art,the neutral gas molecules of the process gas when subjected to thesestrong electric fields lose electrons, and leave behind positivelycharged ions. As a result, positively charged ions, negatively chargedelectrons and neutral gas molecules are contained inside the plasma. Inaddition, a sheath voltage is typically generated directly above thesubstrate, which causes the ions to accelerate towards the substratewhere they, in combination with neutral species, activate the processingreaction.

To further illustrate the process, FIG. 4 shows a flow diagram of therelevant operations involved in processing a substrate in a plasmareactor (e.g., plasma reactor 100). Prior to processing, conventionalpre-processing operations, which may involve the egress and ingress ofsubstrates, are performed. The exemplary process typically takes fivesteps. The first step 201 involves pumping the process chamber to thedesired pressure. The second step 202 involves flowing a processing gasinto the process chamber and allowing the pressure to stabilize. Oncethe gas is stable, the third step 204 ignites the plasma in theprocessing gas. After the plasma is ignited, the fourth step 206stabilizes the plasma to a specific pressure inside the chamber. Afterthe chamber pressure has been stabilized, the fifth step 208 processesthe substrate.

Referring back to FIGS. 1 and 2, plasma processing reactor 100 furtherincludes a confinement ring 130, which is generally configured toconfine a plasma to the area above the substrate 114. As shown in FIG.2, a first portion of the confinement ring 130 is positioned around theouter periphery of the upper electrode 104 and a second portion ispositioned to surround the gap 111 between the upper electrode 104 andthe lower electrode 106 to enclose at least a portion of the activeregion above the substrate 114. The confinement ring 130 is alsosymmetrically disposed around the periphery of the substrate 114 toproduce more uniform processing.

As illustrated, a gap 132 is typically formed between a bottom edge 134of the confinement ring 130 and the lower electrode 106. The gap 132 isgenerally provided to control the conductance of exhaust gases whilesubstantially confining a plasma to the volume defined by the upperelectrode 104 and the confinement ring 130. Preferably, the bottom edgeof the confinement ring 130 is evenly spaced from the top surface of thelower electrode 106 (e.g., parallel) so that an even distribution ofgases at the surface of the substrate 114 may be maintained.

The size of gap 132 generally determines the rate at which exhaust gasesare removed from the active region during processing. While not wishingto be bound by theory, it is believed that too small a gap may impedethe flow of gases which may lead to non-uniform etch rates and particlecontamination along the periphery of the substrate. Further, it isbelieved that too large a gap may not properly confine the plasma to anappropriate volume, which may also lead to non-uniform etch rates (e.g.,a non-uniform plasma). Further still, it is generally believed that thegap plays an important role in controlling the pressure inside theactive region above the substrate. That is, the pressure is inverselyproportional to the exhaust rate, where a decrease in the conductancecorresponds to an increase in pressure, and an increase in theconductance corresponds to a decrease in pressure. Accordingly, the sizeof the gap is preferably configured to balance the desired conductancewith the desired pressures.

FIGS. 1 and 2 also illustrate a linear drive assembly 150 configured formoving the confinement ring 130 between the upper electrode 104 andlower electrode 106, in accordance with one embodiment of the presentinvention. By moving the confinement ring 130 up and down duringprocessing, the conductance of the etchant source gas out of the plasmaprocess chamber 102 may be increased or decreased to keep the pressurein the pressure ranges desired for processing. By way of example, thepressure may be adjusted to accommodate temperature fluctuations thatoccur during a run of substrates thereby maintaining substrate tosubstrate uniformity. Furthermore, the linear drive assembly 150 can beconfigured to move the confinement ring up and down for the ingress andegress of substrate 114.

The linear drive assembly 150 generally includes a first gear 152 and aplurality of second gears 154. Both first gear 152 and the plurality ofsecond gears 154 are rotatably supported by a cover 156 of processchamber 102. Furthermore, the plurality of second gears 154 areoperatively engaged with first gear 152. Linear drive assembly 150 alsoincludes a plurality of positioning members 158 each having a firstportion 160 and a second portion 162. Each of the positioning members158 are parallel to one another. Each of the first portions 160 aremovably coupled to one of the second gears 154 to allow movement of thepositioning members 158 in a linear direction 166. Each of the secondportions 162 are fixed to the confinement ring 130. As shown in FIG. 1,the linear direction 166 is perpendicular to the plane created by thetop surface of substrate 114. Additionally, seals 175 are generallyprovided between the positioning members 158 and the cover 156 to sealthe interface to eliminate leaks.

Moreover, the linear drive assembly includes a motor 161 and a drivinggear 163, which is fixed to motor 161. Motors are well known to thoseskilled in the art, and therefore will not be discussed herein forbrevity's sake. The driving gear 163 is operatively engaged with thefirst gear 152, and configured for driving the first gear 152 when themotor is actuated. Essentially, motor 161 drives driving gear 163,driving gear 163 drives first gear 152, first gear 152 drives theplurality of second gears 154, and the plurality of second gears 154move the corresponding positioning members 158 in linear direction 166,which as a result moves the confinement ring 130 in linear direction 166between upper electrode 104 and lower electrode 106.

The direction that the positioning members 158 move along the linearpath is generally determined by the direction of rotation of the secondgears 154. By way of example, the linear drive assembly 150 may beconfigured to move the positioning member 158 up when the second gears154 are rotated clockwise and down when the second gears 154 are rotatedcounter clockwise.

Referring to FIG. 2, the plurality of positioning members 158 arethreadably coupled to the plurality of second gears 154. That is, thepositioning members 158 and the second gears 154 are fitted with screwthreads, which move the positioning members 158 in the linear directionwhen the second gears 154 are rotated. The second gears 154 generallyinclude a nut portion 170 having an internally threaded surface, and thepositioning members 158 generally include a thread portion 172 having anexternally threaded surface. The externally threaded surface of each ofthe positioning members 158 is configured to mate with the internallythreaded surface of a corresponding second gear 154. Correspondingly,when the second gears 154 are rotated, the threaded portion 172 of thepositioning members 158 travel through the nut portion 170 of therotating second gears 154. One particular advantage of the threads arethat they are constantly engaged and thus permit very precise movementsto be made.

Further, the positioning member/second gear arrangement is generallyarranged so that when the nut portion 170 has made one revolution, thepositioning member 158 has moved one full thread. As is well known tothose skilled in the art, the distance between corresponding points onadjacent threads measured along the length of the screw is generallyreferred to as the pitch. Thus, when the nut portion 170 makes onerevolution, the positioning member 158 is moved the distance of thepitch. By way of example, if the screw threads are cut at 32 threads perinch, then one turn of the second gear (e.g., nut portion 170) moves thepositioning member 158 {fraction (1/32)} of an inch. As can beappreciated, the cut of the threads may be arranged to provide increasedresolution. That is, a greater number of threads per inch tends to allowsmaller incremental movements of the positioning member 158, which inturn allows finer adjustments in pressure. By way of example, a threadhaving between about 10 to about 40 threads per inch works well.However, it should be noted that this is not a limitation and that theamount of threads per inch may vary according to the specific design ofeach process chamber.

To further discuss the features of the present invention, FIG. 3illustrates a top view of linear drive assembly 150 of plasma reactor100. As mentioned, the linear drive assembly 150 includes first gear152, the plurality of second gears 154, the positioning members 158 andthe driving gear 164. The plurality of second gears 154 and the drivinggear 164 are generally disposed about the periphery of the first gear152. For the most part, the movement of the second gears 154 aresynchronized with one another. That is, the direction of movement (e.g.,clockwise or counter clockwise) and the magnitude of the movement (e.g.,amount of teeth that are moved) are the same.

While the linear drive assembly 150 is shown and described as usingexternal spur gears, it will be appreciated that other gearconfigurations may also be used to accommodate different processchambers or to conform to other external factors necessary to allowlinear movements. For example, internal gears (e.g., planetary gears)may also work well. If internal gears are used, the plurality of secondgears and the driving gear would be disposed about the inner peripheryof the first gear.

As shown in FIG. 3, the linear drive assembly 150 includes three secondgears 154 and three positioning members 158. As is well known to thoseskilled in the art, three points define a plane and therefore it ispreferable to have three positioning members moving the confinementring. The three positioning members 158 are configured to move theconfinement ring 130 orthogonal to its center of gravity thereby keepingthe confinement ring 130 balanced and level. As shown, each of thesecond gear/positioning member arrangements are symmetrically spacedaround the first gear 152, and each of the positioning members 158 areaxially oriented in the center the corresponding second gear 154. Itshould be noted that the present invention is not limited to threepositioning members and any number of positioning members may be usedthat are suitable for moving the confinement ring, while keeping itbalanced.

As is well known to those skilled in the art, in order for all of thegears to mesh properly, i.e., turn without slippage, the gears have tobe configured with similar teeth that are about the same size.Furthermore, a small gap between gears is typically provided forsmoother and quieter movements between meshed gears. One particularadvantage of the gear assembly is that the gears are constantly meshedtogether and therefore there is generally no creep or slip, and thusvery precise movements may be made.

One important factor in determining the sensitivity and resolution ofthe linear drive assembly is in the selection of the appropriate geardimensions (e.g., teeth). It is generally believed that the greater theamount of teeth the greater the resolution. That is, the greater theamount of teeth, the smaller the incremental changes in distance movedby the positioning member and thus smaller changes in pressure. Inessence, every gear has x number of teeth resolution. To elaboratefurther, the amount of teeth can be described as individual segments ofthe gear. By way of example, if the second gear has 10 teeth then thesecond gear can be broken up into 10 segments. These segments correspondto incremental movements of the second gear. If only one tooth is moved,then the second gear moves only one segment, and thus the second gearmakes only {fraction (1/10)} of a rotation. Because of the engagementbetween the second gear and the positioning member, the positioningmember correspondingly moves only {fraction (1/10)} of the pitch. If thepitch is {fraction (1/32)} of an inch, then the positioning member willmove {fraction (1/320)} of an inch. By way of example, a second gearhaving between about 10 to about 48 teeth work well. However, it shouldbe noted that this is not a limitation and that the amount of teeth onthe second gear may vary according to the specific design of eachprocess chamber.

The gears may be formed from any suitable material such as metals andplastics, and may be manufactured using any known process such ascasting, forging, extrusion, injection molding, and the like. However,if the gears or the cover of the process chamber encounter thermalexpansion (e.g., if the temperature is high) it may be necessary to formthem out of materials with substantially the same thermal expansioncoefficient so that they will expand at about the same rate. This isgenerally not a factor if the thermal expansion is small because the gapbetween gears is typically larger than the amount of thermal expansion.Further, a lubricant or oil may also be used between gears to reduce theeffects of thermal expansion, as well as, to reduce wear between matinggears.

As mentioned, the gears are rotatably supported by the process chambercover. In one embodiment, bearing gears that allow the gears to rotatefreely are used. As shown in FIG. 3, the first gear 152 is configured asa concentric ring having an inner periphery that is in cooperation witha set of bearings 180. More particularly, the set of bearings 180 aredisposed between the inner periphery of the first gear 152 and a portion182 of the cover 156. Accordingly, the portion 182 of the cover 156 maybe used as a passage way for gas ports, sensors, manometers, etc.Bearing gears are well known and for the sake of brevity will not bediscussed in any more detail. Furthermore, the second gears are rigidlyfixed to the cover of the process chamber. In one implementation, thrustbearings are used to fix the second gears to the cover of the processchamber.

A linear drive assembly (e.g., 150) is generally part of a closed loopcontrol system that is configured to reduce pressure fluctuations insidea process chamber. By way of example, a plasma processing apparatus maybe configured to include a pressure sensor for measuring pressuresinside the active region above a substrate, and a controller or centralCPU for monitoring the measured pressures. Both a motor of the lineardrive assembly and the pressure sensor are operatively coupled to thecontroller. The pressure sensor is configured to produce an electricalpressure signal corresponding to the measured pressure. The controlleris configured to receive the electrical pressure signal from thepressure sensor and to send a corresponding electrical control signal,which is based at least in part on the received signal, to the motor.Furthermore, the motor is configured to receive and implement theelectrical control signal sent by the controller. The electrical controlsignal generally relates to a specific direction and an incrementalchange in position for the motor. Pressure sensors, controllers andmotors are well known in the art, and therefore will not be described indetail.

In accordance with another embodiment of the present invention, thelinear motion of a linear drive assembly is configured to control thegap between the upper electrode and the substrate. In this particularembodiment, the positioning members are fixed to the upper electrode,rather than the confinement ring. Correspondingly, the linear driveassembly is arranged to move the upper electrode up and down to adjustthe volume of the active region above the substrate. By adjusting thevolume, various parameters associated with plasma processing, such asthe plasma density and pressure, may be maintained at desired levels forprocessing.

To facilitate discussion of this aspect of the present invention, FIG. 5shows plasma reactor 100 including a linear drive assembly 700 that isconfigured for moving the upper electrode 104 inside the process chamber102. In this figure, the linear drive assembly 700 is produced inaccordance with the teachings of the invention set fourth above withregards to FIGS. 1-4 and therefore will only be described in brief.

The linear drive assembly 700 generally includes a first gear 702 and aplurality of second gears 704. Both first gear 702 and the plurality ofsecond gears 704 are rotatably supported by the cover 156 of processchamber 102. Furthermore, the plurality of second gears 704 areoperatively engaged with first gear 702. Linear drive assembly 700 alsoincludes a plurality of positioning members 706 having a first portion710 and a second portion 712. The first portion 710 is movably coupledto the second gear 704 in a linear direction 166, and the second portion712 is fixed to the upper electrode 104. As shown, the linear direction166 is perpendicular to the plane created by the top surface ofsubstrate 114. Furthermore, the positioning members 706 are threadablycoupled to second gears 704. As mentioned previously, the positioningmembers 706 and the second gears 704 are fitted with screw threads whichmove the positioning members 706 in the linear direction 166 when thefirst gear 702 is rotated.

Moreover, the linear drive assembly 700 includes a motor 161 and adriving gear 163, which is fixed to motor 161. The driving gear 163 isoperatively engaged with the first gear 702, and configured for drivingthe first gear 702 when the motor 161 is actuated. Essentially, motor161 drives driving gear 163, driving gear 163 drives first gear 702,first gear 702 drives the plurality of second gears 704, and theplurality of second gears 704 move the corresponding positioning members706 in linear direction 166, which as a result moves the upper electrode104 in the linear direction 166.

Although the linear drive assembly has been shown and described asmoving a confinement ring or an upper electrode, it will be appreciatedthat other components may also be moved to accommodate differentprocesses. For example, the linear drive assembly may be used to movethe lower electrode. Furthermore, it should be noted that the presentinvention is not limited to moving components inside the processchamber. For example, the linear drive assembly may be used to move anantenna or an electrode that is disposed outside the chamber. If thistype of system is used, the linear drive assembly is generally coupledto a frame of the plasma reactor, rather than to the cover of theprocess chamber as shown. Additionally, it should be understood that thelinear drive assembly is not limited to moving one component and may beused to move a plurality of components. For example, the linear driveassembly may be arranged to move a plurality of confinement rings or acombination of components such as the confinement ring and the upperelectrode.

In accordance with another embodiment of the present invention, thelinear motion of the linear drive assembly is configured to move boththe confinement ring and the upper electrode. In this manner, increasedcontrol of various parameters associated with processing may beobtained. For example, moving the confinement ring and upper electrodecan change the pressure and plasma density inside the active area abovethe substrate. Therefore, either of the bodies may be moved to maintainsubstrate to substrate uniformity.

To facilitate discussion of this aspect of the present invention, FIGS.6 & 7 show plasma reactor 100 including a linear drive assembly 800 thatis configured for moving multiple bodies inside the process chamber 102.In this figure, the linear drive assembly 800 is produced in accordancewith the teachings of the invention set fourth above with regards toFIGS. 1-5. Thus, the linear drive assembly 800 is configured for movingthe confinement ring 130 between the upper and lower electrode 104 and106 and for moving the upper electrode 104 inside the process chamber102 (both with increased movement control) to control various parametersassociated with processing.

The linear drive assembly 800 generally includes a first gear 802 and aplurality of second gears 804. Both first gear 802 and the plurality ofsecond gears 804 are rotatably supported by the cover 156 of processchamber 102. Furthermore, the plurality of second gears 804 areoperatively engaged with first gear 802. Linear drive assembly 800 alsoincludes a plurality of third gears 806 and a plurality of fourth gears808, which are both rotatably and rigidly supported by process chamber102. A first set of positioning members 810 are movably coupled to thethird set of gears 806 and a second set of positioning members 812 aremovably coupled to the fourth set of gears 808. Both sets of positioningmembers 810 and 812 are movably coupled in a linear direction 166. Asshown, the linear direction 166 is perpendicular to the plane created bythe top surface of substrate 114. Furthermore, the first set ofpositioning members 810 are fixed to the confinement ring 130 and thesecond set of positioning members 812 are fixed to the upper electrode102.

Moreover, the second gears 804 are movably coupled to the processchamber 102 and are configured for engagement and disengagement with thethird gears 806 and the fourth gears 808. More particularly, the secondgears 704 have at least two positions on the cover of process chamber102. A first position (as illustrated) causes the second gear 804 to beoperatively engaged with the third gears 806 and a second positioncauses the second gear 804 to be operatively engaged with the fourthgears 808. In one embodiment, the second gears 804 are configured toslide between these positions in a groove disposed in cover 156. Aclutch is also provided, in this embodiment, to move the second gearsbetween positions to connect and disconnect the second gears from thethird and fourth gears. In one implementation, the clutch is configuredto be part of a closed loop process that automatically engages anddisengages the second gears 804. Clutches are well known in the art, andtherefore, for the sake of brevity will not described in detail.

Additionally, the linear drive assembly includes a motor 161 and adriving gear 163, which is fixed to motor 161. The driving gear 163 isoperatively engaged with the first gear 802, and configured for drivingthe first gear 702 when the motor 161 is actuated. When the second gears804 are engaged with the third gears 806, motor 161 drives driving gear163, driving gear 163 drives first gear 802, first gear 802 drives theplurality of second gears 804, and the plurality of second gears 804drive the plurality of third gears 806, the third gears correspondinglymove the corresponding positioning members 810 in the linear direction166, which as a result moves the confinement ring 130 in the lineardirection 166 between upper electrode 104 and lower electrode 106. Whenthe second gears 804 are engaged with the fourth gears 808, motor 161drives driving gear 163, driving gear 163 drives first gear 802, firstgear 802 drives the plurality of second gears 804, and the plurality ofsecond gears 804 drive the plurality of fourth gears 808, the fourthgears 808 correspondingly move the corresponding positioning members 812in the linear direction 166, which as a result moves the upper electrode102 in the linear direction 166.

To elaborate further, the first set of positioning members 810 arethreadably coupled to third gears 806 and the second set of positioningmembers 812 are threadably coupled to the fourth gears 808. As mentionedpreviously, the positioning members and the corresponding gears arefitted with screw threads which move the positioning member in thelinear direction when the corresponding gears are rotated.

Further, the plurality of second gears 804 and the driving gear 163 aregenerally disposed about the periphery of the first gear 802.Accordingly, the movement of the second gears are synchronized with oneanother. That is, the direction of movement (e.g., clockwise or counterclockwise) and the magnitude of the movement (e.g., amount of teeth thatare moved) are the same. Further still, the third set of gears 806 aregenerally disposed proximate the second gears 804 and above theconfinement ring 130 and the fourth set of gears 808 are generallydisposed proximate the second gears 804 and above the upper electrode102. As shown, each of the third gear/positioning member arrangementsand fourth gear/positioning member arrangements are symmetrically spacedaround the first gear, and each of the positioning members are axiallyoriented in the center the corresponding gears.

As with the linear drive assembly described in FIGS. 1-5, the lineardrive assembly described in FIGS. 6 & 7 can be configured with highresolution by adjusting the amount of teeth on the gears and the pitchof the positioning members. Furthermore, the linear drive assembly ofFIG. 6 & 7 may also be part of a control loop system as previouslydescribed.

As can be seen from the foregoing, the present invention offers numerousadvantages over the prior art. Different embodiments or implementationsmay have one or more of the following advantages.

One advantage of the invention is that the linear drive assemblyprovides precise movements having high resolution, high sensitivity andincreased reliability. As a result, components such as the confinementring and the upper electrode can be moved with a greater range ofcontrol. Accordingly, parameters such as wafer area pressure and plasmadensity can be controlled to provide increased process uniformity (i.e.,uniformity across the surface of the substrate and substrate tosubstrate uniformity), which increases substrate throughput, reducesdevice failure, and increases the overall productivity of the substratesbeing processed.

Another advantage of the invention is that it is cost effective. By wayof example, the present invention, using only a single motor, can beconfigured to move multiple bodies within the process chamber. Further,the present invention reduces the amount of consumable parts (e.g.,wear). As a result, the cost of acquiring and maintaining the system isreduced. Another particular advantage of the present invention is thatthe control is in real time, i.e., the linear movements can be madeduring the processing of a single substrate.

While this invention has been described in terms of several preferredembodiments, there are alterations, permutations, and equivalents whichfall within the scope of this invention. By way of example, althoughonly spur gears have been described and shown, it should be understoodthat other gear configurations, such as helical gears, herringbonegears, worm gears, bevel gears, sector gears, belts and/or chains may beused. Additionally, the positioning member/second gear arrangement maybe configured as rack and pinion gears, which are configured to move inthe linear direction. Further, although only a motor with a driving gearis shown and described, it should be noted that other drive mechanismsmay be used. For example, the motor may be directly coupled to the firstgear, or indirectly coupled to the first gear with belts or chains.

It should also be noted that there are many alternative ways ofimplementing the methods and apparatuses of the present invention. Forexample, although the linear drive assembly is described as beingarranged to move the confinement ring and the upper electrode, it shouldbe understood that it may also be configured to move other bodies, suchas the lower electrode. Furthermore, the linear direction may be used tomove bodies in directions other than perpendicular with the substrate.For example, the linear drive assembly may be used to move bodiesparallel to the substrate surface.

Additionally, it is contemplated that the present invention may be usedin any reactor that is suitable for etching or deposition. By way ofexample, the present invention may be used in any of a number ofsuitable and known deposition processes, including chemical vapordeposition (CVD), plasma enhanced chemical vapor deposition (PECVD), andphysical vapor deposition (PVD), such as sputtering. Furthermore, thepresent invention may be used in any of a number of suitable and knownetching processes, including those adapted for dry etching, plasmaetching, reactive ion etching (RIE), magnetically enhanced reactive ionetching (MERIE), electron cyclotron resonance (ECR), or the like.

It is therefore intended that the following appended claims beinterpreted as including all such alterations, permutations, andequivalents as fall within the true spirit and scope of the presentinvention.

1. A plasma processing method, comprising: confining a plasma with aconfinement ring; processing a substrate with said plasma; and movingsaid confinement ring in a linear direction during said processing inorder to effect said processing.
 2. The method as recited in claim 1wherein said confinement ring is moved via a gear drive assembly.
 3. Themethod as recited in claim 1 wherein said confinement ring is moved insaid linear direction in order to control a pressure at a surface ofsaid substrate during said processing.
 4. The method as recited in claim3 wherein said confinement ring is moved in a first linear direction toincrease the pressure at the surface of said substrate during saidprocessing, and wherein said confinement ring is moved in a secondlinear direction opposite the first linear direction to decrease thepressure at the surface of said substrate during said processing.
 5. Themethod as recited in claim 1 wherein a gap is provided between saidconfinement ring and a plane defined by said substrate during saidprocessing, and wherein the size of said gap is changed during saidprocessing by moving said confinement ring in said linear direction, thesize of said gap effecting said processing.
 6. The method as recited inclaim 1 wherein an etching task is employed in said processing toselectively remove materials from predefined areas on a surface of saidsubstrate.
 7. The method as recited in claim 1 wherein a deposition taskis employed in said processing to selectively deposit materials onpredefined areas on a surface of said substrate.
 8. The method asrecited in claim 1 wherein said substrate is held stationary during saidprocessing.
 9. The method as recited in claim 1 further comprising:monitoring a process condition above said substrate during saidprocessing; and moving said confinement ring based on the monitoredprocess condition.
 10. The method as recited in claim 9 wherein theprocess condition is pressure.
 11. The method as recited in claim 9wherein the process condition is temperature.
 12. The method as recitedin claim 9 wherein multiple process conditions are monitored and whereinsaid confinement ring is moved based on said multiple processconditions, the multiple process conditions including at leasttemperature and pressure.
 13. The method as recited in claim 1 furthercomprising: producing an electric field with an electrode; and movingsaid electrode in said linear direction during said processing in orderto effect said processing.
 14. The method as recited in claim 13 whereinsaid electrode is moved in said linear direction in order to adjust thevolume of an active region located above said substrate.
 15. The methodas recited in claim 13 wherein a gap is provided between said electrodeand a plane defined by said substrate during said processing, said gapdefining a process region in which said plasma is both ignited andsustained for processing, and wherein the size of said gap is changedduring said processing by moving said electrode in said lineardirection, the size of said gap controlling a volume of said processregion.
 16. The method as recited in claim 13 wherein the confinementring and electrode are moved via a gear drive assembly.
 17. The methodas recited in claim 13 wherein the confinement ring and electrode areindependently moved during said processing.
 18. A plasma processingmethod, comprising: producing an electric field with an electrode;processing a substrate with a plasma; and moving said electrode in alinear direction during said processing in order to effect saidprocessing.
 19. The method as recited in claim 18 wherein said electrodeis moved via a gear drive assembly.
 20. The method as recited in claim18 wherein said electrode is moved in said linear direction in order toadjust the volume of an active region located above said substrate. 21.The method as recited in claim 20 wherein said electrode is disposedabove or below said substrate during processing, and wherein saidelectrode is coupled to en RF power supply that supplies said electrodewith RF energy.
 22. The method as recited in claim 18 wherein a gap isprovided between said electrode and a plane defined by said substrateduring said processing, said gap defining a process region in which saidplasma is both ignited and sustained for said processing, and whereinthe size of said gap is changed during processing by moving saidelectrode in said linear direction, said gap controlling a volume ofsaid process region.
 23. The method as recited in claim 18 furthercomprising: monitoring a process condition above said substrate duringsaid processing; and moving said electrode based on the monitoredprocess condition.
 24. The method as recited in claim 18 furthercomprising: confining said plasma with a confinement ring; independentlymoving said confinement ring and said electrode in said linear directionduring said processing in order to effect said processing.
 25. Themethod as recited in claim 24 wherein said electrode is moved in saidlinear direction in order to adjust the volume of an active regionlocated above said substrate and wherein said confinement ring is movedin said linear direction in order to control a pressure at a surface ofsaid substrate during said processing.
 26. The method as recited inclaim 25 further comprising: monitoring a process condition above saidsubstrate during said processing; and moving said electrode and saidconfinement ring based on the monitored process condition.
 27. A methodof moving a confinement ring or electrode inside a plasma processchamber, comprising: rotating a first gear; rotating a second gear viasaid rotating first gear when said first gear is operatively engagedwith said second gear; moving a shaft along a linear path via saidrotating second gear, said shaft moving in a first direction when saidfirst gear is rotated clockwise, said shaft moving in a second directionwhen said first gear is rotated counterclockwise; and moving saidconfinement ring or electrode up and down along said linear path viasaid moving shaft.
 28. The method as recited in claim 27 furthercomprising: rotating a third gear via said first rotating gear when saidfirst gear is operatively engaged with said third gear; moving a secondshaft along a linear path via said rotating third gear, said secondshaft moving in a first direction when said first gear is rotatedclockwise, said shaft moving in a second direction when said first gearis rotated counterclockwise; selectively engaging the first gear withthe second or third gear in order to selectively move said electrode andsaid confinement ring; if said first gear is engaged with said secondgear, moving said electrode up and down along said linear path via saidfirst moving shaft; and if said first gear is engaged with said thirdgear, moving said confinement ring up and down along said linear pathvia said second moving shaft.
 29. The method as recited in claim 28further comprising: processing a substrate inside said plasma processchamber, said processing including etching or deposition; andselectively moving said confinement ring and said electrode during saidprocessing.
 30. The method as recited in claim 29 further comprising:processing a substrate inside said plasma process chamber, saidprocessing including etching or deposition; and simultaneously movingsaid confinement ring and said electrode during said processing.
 31. Themethod as recited in claim 27 further comprising: rotating a third gear;rotating a fourth gear via said rotating third gear when said third gearis operatively engaged with said fourth gear; moving a second shaftalong a linear path via said rotating third gear, said second shaftmoving in a first direction when said third gear is rotated clockwise,said second shaft moving in a second direction when said third gear isrotated counterclockwise; moving said electrode up and down along saidlinear path via said moving shaft; and moving said confinement ring upand down along said linear path via said second moving shaft.
 32. Themethod as recited in claim 27 further comprising: processing a substrateinside said plasma process chamber, said processing including etching ordeposition; and only moving said confinement ring during saidprocessing, wherein the size of a gap provided between said confinementring and a plane defined by said substrate is changed during saidprocessing by moving said confinement ring along said linear path, thesize of said gap effecting said processing.
 33. The method as recited inclaim 27 further comprising: processing a substrate inside said plasmaprocess chamber, said processing including etching or deposition; andonly moving said electrode during said processing, wherein the size of agap provided between said electrode and a plane defined by saidsubstrate is changed during said processing by moving said electrodealong said linear path, the size of said gap effecting said processing.